From "Jersey Shore" to "Two and a Half Men" to "The Office," TV is in period of transition that proves everybody is replaceable.

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There's only one Snooki – thank goodness. But even the "Jersey Shore" crew is replaceable.

Updated at 6:27 PM PDT on Tuesday, Jun 28, 2011

As much as we'd like to agree with Pauly D's declaration that he and his "Jersey Shore" cronies are "irreplaceable,” we sadly beg to differ – even if the end of the show is a tantalizing thought.

Pauly D's pronouncement came amid conflicting reports that a new crop of young people willing to act like foolish stereotypes to get on TV might be recruited for fist-pumping duties for Season 6.

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Even looking beyond the insular world of the “Jersey Shore,” television is in the midst of a spate of turnover in major shows, ranging from reality nonsense to sitcoms to dramas. The bottom line is that on TV, as in life, everybody’s replaceable.

The signs of change are all over the tube: Not only has Charlie Sheen been kicked off "Two and a Half Men," his character – a wacky guy named Charlie – reportedly will meet a violent death, meaning he'll never get to meet Ashton Kutcher. Christopher Meloni, meanwhile, is making a relatively controversy-free exit from "Law & Order: SVU,” with Danny Pino and Kelli Giddish set to join the show.

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"Glee" creator Ryan Murphy recently restated his plans to let the current cast graduate after next season (most of the actors are already old enough to have sat for the bar exam) and introduce a new class of McKinley High gleeks. Jennifer Lopez, who, with Steven Tyler, pulled off TV’s most successful double switch since Harry Morgan and Mike Farrell joined "MASH" in 1975, is making rumblings about not returning to "American Idol" next season.

The replacement machinations we're most interested in – the post-Steve Carell version of "The Office" – are getting a tad confusing. The latest reports suggest James Spader, hilarious in the season finale as mind-game-playing job candidate Robert California, will join the show. But California, in this scenario, only will briefly replace Carell's Michael Scott before taking over for Kathy Bates' part-time character, Dunder Mifflin Sabre owner Jo Bennett, because the actress is busy with her fulltime gig on “Harry’s Law.” Got it?

Anyone saying "So what?" to all of this probably views a modest, healthy amount of TV (or – gasp! – none). But for those of us who spend too much time watching, this summer is turning into the equivalent of baseball's winter Hot Stove League, where everybody gets to play general manger – or, in this instance, a harried TV executive.

That’s a testament to some characters who command strong attachments (even if in other cases much of the attention is prompted by on- and off-screen silliness). While the most dedicated TV fans aren't crazy about major alterations to that alternate universe beamed to us on screens big and small, we'll stipulate that change can be good.

Sure, Michael Scott and Snooki may seem irreplaceable to some – but we'd only miss one of them.